Concerning that diode load jack, I have a Collins R-388 (1962 Model) that has that jack. I connected that via a capacitor/resistor curcuit and connected that to a amplifier. The audio out of that connection is unbelievable. Very rich and bassy, unlike the pinched audio out of the R-388. Anyone who has that available that isn't using it is missing a whole lot!.

Concerning that diode load jack, I have a Collins R-388 (1962 Model) that has that jack. I connected that via a capacitor/resistor curcuit and connected that to a amplifier. The audio out of that connection is unbelievable. Very rich and bassy, unlike the pinched audio out of the R-388. Anyone who has that available that isn't using it is missing a whole lot!.

A very nice secret that not many know about. Beautiful audio from the Diode Load"Simply obtain an audio extension cable with an RCA plug on one end from Radio Shack. Place a 470K resistor in series with a 10uf, non-polarized (also available at Radio Shack) capacitor and connect it to one of the screws holding the jumper across the "DIODE LOAD" screws on TB-103. Do not remove the jumper. Connect the other end of the capacitor/resistor network to the center conductor of the RCA cable then ground its shield to the "GND" screw located on TB-103 immediately to the right of the "DIODE LOAD" screws. Plug your cable into the TAPE or AUX jack on your stereo receiver, adjust the tone controls as appropriate and enjoy."

I regard myself as a relatively competent technician when it comes to radio - as well as being a Senior IEEE Member. Looking at what you guys have done with restoring mechanical filters, if I ever wore a hat, I'd take it off to you all. Congratulations - just don't let the chest swell enough to burst the buttons!

Seriously, I'm impressed.

Well, thanks, but it's just a lot of detailed and time consuming work. It's not rocket science. I still have a couple of filters I need to finish off to get the 390A finished. After all, it's a hobby. Who else would do it?

The other thing you can do with the 390A is take the 455 if out, convert it to 12 KHz and use some soundcard software to decode it. Like DReaM or HDSDR, but it's not like listening to the radio, there's a bit of delay which makes it hard to tune, especially in SSB and CW. But AM is pretty good. And if you can figure out the DRM it should be real good. I haven't been able to do that yet.

I do not want to hijack the thread but DRM radio is a real Dream to listen to. Sounds like perfect FM radio over shortwave. I have the DRM software in the Flex radio PowerSDR software. I bought the license to decode and build the dll files needed to operate the DRM.There's a growing number of shortwave stations on the air several hours a day.And Kevin you are probably very correct. Military audio out of the headphones and even the Line out amps built-in the 390A......UNLESS they were modified for hi-fi audio.Hi-fi audio already available from the Diode Load terms on the backFred

From time to time a new thread will ask the question: What's the * BEST * external speaker for Hamateur radio use?

Invariably I'll say something to the effect of having good luck with thrift shop orphans (bookshelf stereo electronics gone kaput, speakers still good) as long as they're of the 4 Ohm persuasion and reasonably efficient. Translation: Single driver bass-reflex with a whizzer cone. Within hours a dissenting opinion will assert that only a proper communications grade speaker designed specifically for SSB / CW use is worth having. Even if they are in the $100.00+ price class. If the advertising specifies communication grade, that's whatcha' want. Like the $2.00 orphan is overpriced. Or the AF amp in the radio is broadband. And a mostly flat response curve is a bad characteristic for a speaker.

Then I wonder if these are the same folks running an All Band WonderTenna. You know what that is... Something that makes you wonder who'd pay $250.00 for an antenna made from $20.00 worth of wire and marketed by an eighth of a page advert in QST that features the word 'miracle'.

What will be best SSB detector project for the R390A receiver? My receiver finally arrived,I have one EAC maded unit on repair bench and after cleanup and repair/readjusting job I will need some decent SSB detector for ham activity..That will be best to build?I would like to build some outside unit, not to mod receiver..For only AM is not a problem, some kind of synchro detectors but with SSB reception..hm..any clues?

I know for existence of this product, nice piece of electronics but unfortunately this is not what I am looking for. I want to built detector by myself, using my knowledge and patience for homebrew electronics...Beside of this detector, and one from Surrey will be possible to find some other somewhere on the net or in drawer?

There was a circuit for a product detector for tube equipment published in the TechnicalTopics column of the RSGB journal RadCom perhaps 10+ years back, along with adiscussion of how to use some of the old boat anchors (including the R-390 IIRC) for CWand SSB with the existing detector.

Not sure just what box my books are in after our recent move - may take me a while todig it out, but if someone locally to you has old issues of RadCom it may beworth looking for it.

A diode detector on AM wants around 10 volts rms carrier to minimise distortion. Most product detectors curl up their toes at that. So I used a 6SJ7 (6AU6 will do) as a Hartley CIO (screen grounded to RF, cathode on a top on the coil)and applied the last IF voltage through a 5 pF to grid 3, which has a low mu: grids 1, 2 and the cathode acting as the CIO. Output from the plate. This works fine: a Norwegian ham didn't like it but I don't think he appreciated that an AM detector needs a lot of volts to avoid distortion and produce enough AGC. Because of that, you can use a very low gain SSB product detector.

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